1. Field of the Invention
The present invention relates to a photoelectric conversion device that outputs light received into an electrical signal and a semiconductor device having the photoelectric conversion device.
2. Description of the Related Art
As a photoelectric conversion device used for detecting an electromagnetic wave, ones having sensitivity in the ultraviolet light region to infrared light region are also referred to as light sensors, in general. Among general light sensors, one having sensitivity in a visible light ray region of a wavelength of 400 to 700 nm is referred to as a visible light sensor, which is variously used for equipment that needs illuminance adjustment or on-off control depending on the living environment (see Patent Document 1: Japanese Published Patent Application No. 2005-129909).
When a color sensor is manufactured with the use of single-crystalline silicon (Si), a color filter is provided on an uppermost surface of a single-crystalline silicon substrate because light is received on the surface side of the substrate. In addition, a color sensor using single-crystalline silicon prevents absorption of an infrared ray with the use of an infrared ray cut filter and is manufactured to have desired spectral sensitivity in many cases.
On the other hand, when the sensor is manufactured using amorphous silicon (a-Si), since an amorphous silicon film can be formed over a substrate, light can enter not only from the substrate surface side but also from the substrate side. In other words, since light can be received by the sensor by transmission through the substrate, light can be introduced into the sensor efficiently. Therefore, an extraction electrode can be provided on another surface of an incidence surface; therefore, the sensor is miniaturized easily. In addition, since an amorphous silicon film hardly absorbs infrared light, it is not necessary to provide the infrared ray cut filter. However, when the color sensor is manufactured using an amorphous silicon film, a color filter is interposed between a photoelectric conversion layer formed of an amorphous silicon film and a substrate.